Double-acting two-stroke-cycle internal-combustion engine.



A. HENNIG.

DOUBLE ACTING TWO-STROKE CYCLE INTERNAL COMBUSTION ENGINE.

APPLICATION FILED AUG.28. 1912. 1,210,801. Patented Jan. 2,1917.

ALBERT HENNIG, OF HAMBURG, GERMANY.

Specification of Letters Fatent.

Patented J an. 2, 1917.

Application filed August 28, 1912. Serial No. 717,507.

To all whom it mag concern:

Be it known that I, ALBERT Ilnxnre, a subject of the Emperor of Germany, residing at Hamburg, Germany, have invented certain new and useful Improvements in Double-Acting Two-Stroke-Cycle Internal- Combustion Engines, ofwhich the following is a specification.

This invention relates to double-acting two-stroke cycle internal combustion engines with pistons runninq in opposite directions and controlling the admission and exhaustports, and relates to engine of this kind wherein there are provided a large doubleacting wm'l-:ing-piston controlling the scavenging air ports and tour smaller singleacting pistons of shorter stroke than the double-actingworking piston, which smaller pistons have their axes parallel and control the exhaust ports, the compression cham bers being each bounded by two smallpistons and the large working piston. By thus distributing the exhaust over two pistons of shorter stroke thanthe large working pisten, the exhaust-ports can be made shorter than would be the case if the said exhaustports were arranged in the working cylinveniently and advantageously carried into practice.

In this drawing, a is the working piston movable in a cylinder (0 having a centrallyarranged annular seriesof ports a (6 which communicate with an annularchamber a extending around the cylinder at. This chamber a and ports a a preferably serve for the introduction into the cylinder at of the scavenging air. These ports a (1 are controlled by the Working piston a whereby they are opened to the spaces at opposite ends of the cylinder a alternately.

The cylinder. a is in communication at each end through passages 0, 0 with two cylinders Z), Z), in which move single-acting pistons Z), Z) controlling annular series of ports 5 Z) which communicate with annular chambers Z) 6 extending around the cylinders D, 5 respectively. The said annular chambers preferably communicate with the exhaust.

The several pistons above mentioned are driven from a crank shaft (Z, the crank d of which drives the working piston a and the cranks (Z (Z which are arranged at an angle'of 180 to the crank (Z and are of shorter throw, drive the pistons Z), 6. The said crank-shaft may be connected to said pistons by suitable intermediate gearing of known construction, "for example, in sucha manner that, at each end of the working cyl- .inder a, the working piston a. moves first toward and then away from the pistons Z), Z). The fuel may advantageously be injected through the passages e, e, for example, in the case of ignition by the heat of compression, when the pistons a, Z), Z) are in the position shown in the upper part of the figure, the injection of fuel into the lower combustion-chamber 0 taking place when the crankshaft has turned through an angle of 180.

It is known that in two-stroke-cycle engines, especially in those which work with compression-ignition (Diesel), the efficiency and the quality of the combustion are de pendent on the completeness of the scavenging.

In order to obtain good scavenging, the scavenging air must be prevented from mixing with the gaseous products ofcombustion, 2'. e. penetrating intothem and thus only diluting them, the intention being to expel the gaseous products of combustion by means of the scavenging air without the latter mixing with them. For this purpose, the scavenging-air ports a (4 should only be opened by the working piston a after a part of the exhaust gases has escaped through the exhaust ports 6 ZF, and the pressure in the working cylinder a corresponds to the pressure of the scavenging air. In the engine shown in the accompanying drawing, on account of the considerably greater stroke of the scavenging air-piston a, the scavenging air ports a (E, are longer than. the exhaust-ports b Z) and also larger scavenging areas are opened much more rapidly than in the case with the usual two-stroke cycle arrangements. Notwithstanding the shorter stroke of the exhaust pistons Z), Z)

are still large enough, since the circumference of the cylinder 18 the determining factor for the cross-section of the port and the from the scaven in air 0 linder a into the two exhaust cylinders Z), Z), is eddying to be feared on account of the change of direction which the exhaust gases experience. It 'is to be assumedthat the exhaust cylinders are worse scavenged'than the scavenging air cylinders. For that reason in the new arrangement the volume of the exhaust cylinder is kept as small as possible and the stroke reduced.

It is known that the cylinders of double acting engines, by reason of the rapid generation of heat, are very liable to be injured by excessive temperatures, especially when it is sought to obtain higher mean pressures. Now ithas not heretofore been possible in practice to make the linings of the cylinders of" double-acting two-stroke-cycle engines freely extensible in a satisfactory manner.- These excesslve temperatures result in warping and cracking of the cylinder more especially at the ports,.which either cannot cool a at all or can only partly cool. The hot gases do not reach the scavenging air ports because they are already on their way-toward the open exhaust ports before the former are opened. Since the latter is also cooled from the interior in the usual manner with water, undesirable transmission of heat to the stuffing boxes is not to be feared.

The temperature of the scavenging air sweeping along the cylinder will gradually rise, the exhaust cylinders will become the hottest and damage can here be avoided in a known manner, by freely expansible cylinder-linings. The expansion of the cylinders by reason of the exhaust-cylinders being short will be verysmall, the short exhaust-cylinders will easily cool completely and the short, small exhaust pistons are more certain in operation than one large one, especially with the short stroke.

In motors with compression-ignition, which are designed for propelling ships, the slow speed causes trouble. The compression chamber with the slow speed and the low mean pressures soon becomes so cold Copies ofthis patent may be obtained for that ignition does not take place. This (3001-; mg of the compression chamber isincreased by the fact that, with atwo stroke-cycle, the.

scavenging air, and witha four-stroke-cycle, the alr drawn-1n, 18 almost always introduced directlyinto the compression-charm ber, so that here the air, whereit is still the coolest, impinges against the walls of the compression-chamber. In the newengine, thecompression-chamber is kept warm by the main body of the hot exhaust gases which there give up a large part of their heat by reason of the alteration of direction and the edclying. Also the scavenging air which follows ishere already so preheated that no considerable lowering of temperature. can

occur during slow running. 7 o

Engines the cylinders of which have the r axes parallel, especially those -w1thshortstroke exhaust-cylinders, can be easily dismounted. 'Also inthe present arrangement one has a large amount of freedom in respect of the dimensions of the crank-shaft. If the scavenging and exhaust-cylinders are coaxial, the centers of the three-throw crank fall too near together. A further advantage of the new arrangement is that all the cylinders and also the engine-frame are relieved from the load due to the force exerted by the piston. 'Th6 piston-forces are transmitted directly by the lin-kwork to the three-throw crank-shaft. i The new engine by reason of the short stroke of the exhaust piston is built very short. It is of course also possible to control the exhaust ports by the large double acting piston and the air ports by the four small pistons with parallel axes.

Claim:

In a double acting, two-stroke cycle internal combustion engine having cylindersprovided with scavenging air and exhaust ports,

the combination of a large double acting working piston controlling the scavenging air ports with four similar smaller single acting working pistons, said smaller pistons smaller pistons and the working piston bounding each of the compression'chambers of the engine, substantially as described.

In testimony whereof I aflix my signature 1n presence of two witnesses.

I ALBERT nENNic.

Witnesses:

ERNEST HJL'. MUMNENHoFF, EDUARD P. R; I-Iorr.

five cents 'each, byaddressingthe Commissioner of Patents,

Washington,D.0. 

